The present invention relates to three dimensional (3D) directional velocity measurements of gases flowing through a passage of a system such as at an inlet or exhaust of a gas turbine via arrays of laser beams and detectors set up in two parallel planes with a distance. A method and the set up of arrays of laser beams and detectors are also presented. 3D measurements are important in improving performance, diagnostics, and modeling of the system.
Turbo-machine systems include a rotary component that is driven by a working fluid, such as a gas. For example, gas turbine engines generate power by compressing atmospheric air, adding fuel to the compressed air, combusting the mixture of fuel and air, and driving a turbine with the mixture of combusted gases. The working fluid continuously passes through the compressor, combustor and turbine, and is discharged as it passes turbine.
The working fluid flowing through a gas turbine engine holds information about the operation and performance of the engine. The velocity and direction of the working fluid, the temperature and distribution of temperatures in the working fluid, and the chemical composition of the working fluid reflect the condition and performance of the engine. For example, the exhaust gas provides information regarding the combustion temperature in the combustor, the performance and efficiencies of gas turbine, the constituents of the combusted gases flowing through turbine, and other performance parameters of the system. The 3D characteristic of velocity, flow directions, temperature and components of the working fluid across and cross-section of the flow passage of the working fluid and over time can be particularly telling of the condition and performance of the engine. 3D characteristic of fluid may also be used improving the mathematical modeling of the overall system, e.g., gas turbine.
The characteristics of working fluid are difficult to measure due to the extreme temperatures, pressures and other flow conditions in a gas turbine engine. Temperatures of the exhaust gases from a typical industrial gas turbine engine may be, for example, 900 to 1200 degrees Fahrenheit (° F.) (482 to 649 degrees Celsius ° C.). The mass flow of the exhaust gases may be, for example, 300 to 975 pounds per second (lb/sec) (136 to 442 kg/sec). Swirl in the exhaust creates difficulties in measuring and analyzing the working fluid. Conventional temperature probes, such as thermocouples, and arrays of probes have not been capable of measuring the temperature distribution of exhaust gases over an extended period of operation of the gas turbine engine.
The conditions of the working fluid at the turbine exit and in the exhaust are conventionally not directly measured but are calculated. The calculated conditions are used to control a gas turbine engine. The calculations of the conditions of the working fluid are generally based on engine parameters such as power output, pressure ratio of the compressor, fuel flow to the combustor and ambient conditions. The calculations of the working fluid are based on assumptions and approximations that may not accurately model the actual flow conditions.
The conventional calculations of the conditions of the working fluid do not provide detailed information regarding actual operating conditions in specific locations in the engine, such as a poorly performing combustion can, or instantaneous conditions of the working fluid. Further, the calculations do not provide information regarding distribution of the flows passing through a turbo-machine, such in the exhaust of a gas turbine engine. There is a long felt need to directly measure the flow of a working fluid in or from a turbo-machine in two-dimensions (2D) or in three dimensions (3D) to provide 2D and 3D maps showing the flow and particularly the distribution of the flow in cross-section and over time.